Anti-whalers in blow-up with Japanese

Anti-whaling campaigners and the crew of a Japanese whaling ship have had a violent clash at sea, with the activists hurling containers of rotten butter and paint and getting sticks and teargas in return.

Sea Shepherd's Steve Irwin vessel was shadowing the Yushin Maru 2 in the Antarctic Ocean when the confrontation occurred on Sunday.

The Japanese Fisheries Agency says the activists threw more than 40 bottles of rotten butter and paint at the whaling ship.

Steve Irwin captain Paul Watson told the ABC that the Japanese returned fire with concussion grenades and teargas.

"They have been using concussion grenades on us," Mr Watson said.

"Today they used, also for the first time, teargas which they have in these large canisters on backpacks."

It was the latest incident in the long-running battle between the activists and Japanese.

Two weeks ago three Australians illegally boarded the Shonan Maru 2 off the West Australian coast in an effort to disrupt the Japanese whalers.